This changes the albedo of the planet significantly, reducing total insolation and resulting in cooling.
In models that include indirect effects, different treatments of the indirect effect are used, including
changing the albedo of clouds according to an off - line calculation (e.g., Tett et al., 2002) and a fully interactive treatment of the effects of aerosols on clouds (e.g., Stott et al., 2006b).
It's an approximation, but we should just have a new spherical system with an albedo a bit different from the first one, and it seems to me implausible that a few CO2 ppm added could
change the albedo of this entire new system.
These algae can
change the albedo of snow, affecting the rate of Arctic snowmelt.
This is largely because melting sea ice
changes the albedo of high latitude oceans, and to a lesser extent because an inversion prevails at high latitudes, especially in winter, whereas at low latitudes the heating is convectively mixed througout the troposphere.
CO2
changes the albedo of the atmosphere in frequencies that are visible only to snakes and infrared imaging instruments.
Read more: Stanford University Aerosols Also Implicated in Glacier Melting, Changing Weather Patterns Other research examining the effects of soot on melting glaciers and changing weather pattens in South Asia has reached similar conclusions: Beyond increasing atmospheric warming, because the soot coats the surface of the snow and ice
it changes the albedo of the surface, allowing it to absorb more sunlight and thereby accelerating melting.
This black carbon
changes the albedo of the ice, causing it to reflect less sunlight and absorb more heat.
Black carbon can have another indirect effect by
changing the albedo of snow and ice, but that's not the topic of this post.
Not exact matches
They found that in regions where the amount
of snowfall was low and any snow that did settle was sublimating away, enough dust would have accumulated to
change the surface
albedo sufficiently so that the Earth absorbed sunlight and thawed (Journal
of Geophysical Research — Atmospheres, DOI: 10.1029 / 2009jd012007, in press).
Their analysis reveals that the conversion
of broadleaved forests to coniferous forests caused significant
changes in evapotranspiration, the evaporation
of water through leaves, and
albedo, the amount
of solar energy reflected from the Earth back into space.
The impact
of grain size on
albedo — the ratio between reflected and incoming solar radiation — is strong in the infrared range, where humans can't see, but satellite instruments can detect the
change.
The boundaries
of ancient valley walls are defined by textural and
albedo changes and are also associated with lateral river migration.
These factors have decreased the region's
albedo, or the fraction
of incoming light that Earth reflects back into space — a
change that the CERES instruments are able to measure.
A diminishing
albedo in Arctic sea ice can be considered both the cause and effect
of changes in sea ice.
Also about the ice -
albedo feedback within 1K temperature oscillation the
albedo will
change of, let us say, 10 %, so for an increase
of 1K the
albedo will decrease from A = 0.3 to A = 0.27.
I guess I am surprised that with better understanding
of the importance
of water vapor feedback, sulfate aerosols, black carbon aerosols, more rapid than expected declines in sea ice and attendant decreases in
albedo, effects
of the deposition
of soot and dust on snow and ice decreasing
albedo, and a recognition
of the importance
of GHGs that were probably not considered 30 years ago, that the sensitivity has
changed so little over time.
What G&T are missing is the linear effect
of water vapour accelerating the ice
albedo effect
of change in size
of the sea ice sheets.
Lynn, the increase
of temperatures in the Arctic, is mainly the result
of an inflow
of warmer air from lower latitudes (with the current AO) and the
change in
albedo (mainly in summer).
That's pretty alarming, especially when considered in the context
of other positive feedbacks including
changes in
albedo from melting icecaps and release
of carbon and methane from thawing permafrost.
Model performance in reproducing the observed seasonal cycle
of land snow cover may provide an indirect evaluation
of the simulated snow -
albedo feedback under climate
change.
I can't tell where you got the figure but -3.5 W / m2 is about right for current understanding
of «boundary condition» land
albedo change between pre-industrial and LGM.
This method tries to maximize using pure observations to find the temperature
change and the forcing (you might need a model to constrain some
of the forcings, but there's a lot
of uncertainty about how the surface and atmospheric
albedo changed during glacial times... a lot
of studies only look at dust and not other aerosols, there is a lot
of uncertainty about vegetation
change, etc).
There was more ice around in the LGM and that
changes the weighting
of ice -
albedo feedback, but also the operation
of the cloud feedback since clouds over ice have different effects than clouds over water.
You've hit on one
of the weaknesses
of the paper, as the model they use admittedly doesn't model
changes in
albedo (at least, not as a model output).
I guess a relatively small
change in temperatures wouldn't affect the
albedo of a flat highland near the poles.
The measured energy imbalance accounts for all natural and human - made climate forcings, including
changes of atmospheric aerosols and Earth's surface
albedo.
Specification now
of a CO2 target more precise than < 350 ppm is difficult and unnecessary, because
of uncertain future
changes of forcings including other gases, aerosols and surface
albedo.
The
albedo and CO2 feedbacks amplified weak orbital forcings, the feedbacks necessarily
changing slowly over millennia, at the pace
of orbital
changes.
In addition, since the global surface temperature records are a measure that responds to
albedo changes (volcanic aerosols, cloud cover, land use, snow and ice cover) solar output, and differences in partition
of various forcings into the oceans / atmosphere / land / cryosphere, teasing out just the effect
of CO2 + water vapor over the short term is difficult to impossible.
I was interested not so much in the forcing effect
of clouds themselves so much as the
change in
albedo which might result from a
change in the overall extent
of global cloud cover.
However, the Management and Guest Contributors at WUWT accept the basic truth that CO2, water vapor, and other «greenhouse gases» are responsible for an ~ 33ºC boost in mean Earth temperature, that CO2 levels are rising, partly due to our use
of fossil fuels, that land use has
changed Earth's
albedo, and that this human actvity has caused additional warming.
eg how big is the «expected» impact on the climate / temps etc from that kind
of change / feedback in ASI
albedo
The model considers all relevant feedback processes caused by
changes of water vapour, lapse - rate, surface
albedo or convection and evaporation.
While the local, seasonal climate forcing by the Milankovitch cycles is large (
of the order 30 W / m2), the net forcing provided by Milankovitch is close to zero in the global mean, requiring other radiative terms (like
albedo or greenhouse gas anomalies) to force global - mean temperature
change.
This estimate is generous to the GCR hypothesis, since the cumulus - to - water
albedo shift exaggerates the true
change of low clouds, and I need bond
albedos in my calculation and I'm using visible
albedos.
Other factors would include: —
albedo shifts (both from ice > water, and from increased biological activity, and from edge melt revealing more land, and from more old dust coming to the surface...); — direct effect
of CO2 on ice (the former weakens the latter); — increasing, and increasingly warm, rain fall on ice; — «stuck» weather systems bringing more and more warm tropical air ever further toward the poles; — melting
of sea ice shelf increasing mobility
of glaciers; — sea water getting under parts
of the ice sheets where the base is below sea level; — melt water lubricating the ice sheet base; —
changes in ocean currents -LRB-?)
If we allow that all those clouds are cumulus with an
albedo of 0.8 and that they block water with an
albedo of 0.1, that translates to a
change in global
albedo of 0.014.
A conceptual model is presented where, through a number
of synergistic processes and positive feedbacks,
changes in the ultraviolet / blue flux alter the dimethyl sulphide flux to the atmosphere, and in turn the number
of cloud condensation nuclei, cloud
albedo, and thus sea surface temperature.
I guess I am surprised that with better understanding
of the importance
of water vapor feedback, sulfate aerosols, black carbon aerosols, more rapid than expected declines in sea ice and attendant decreases in
albedo, effects
of the deposition
of soot and dust on snow and ice decreasing
albedo, and a recognition
of the importance
of GHGs that were probably not considered 30 years ago, that the sensitivity has
changed so little over time.
Pretty much all existing GCMs take into account
changes in cloud
albedo effects (though these are still characterized by a fairly high level
of uncertainty).
On the possibility
of a
changing cloud cover «forcing» global warming in recent times (assuming we can just ignore the CO2 physics and current literature on feedbacks, since I don't see a contradiction between an internal radiative forcing and positive feedbacks), one would have to explain a few things, like why the diurnal temperature gradient would decrease with a planet being warmed by decreased
albedo... why the stratosphere should cool... why winters should warm faster than summers... essentially the same questions that come with the cosmic ray hypothesis.
In our own modelling, we have improved the calculations to reduce the amount
of numerical diffusion (which helped a lot), and increased resolution (which also helped), but
changes to the ocean model also have a big impact, as do Arctic cloud processes and surface
albedo parameterisations, so it gets complicated fast.
What G&T are missing is the linear effect
of water vapour accelerating the ice
albedo effect
of change in size
of the sea ice sheets.
For example, the ice age — interglacial cycles that we have been locked in for the past few million years seem to be triggered by subtle
changes in the earth's orbit around the sun and in its axis
of rotation (the Milankovitch cycles) that then cause ice sheets to slowly build up (or melt away)... which
changes the
albedo (reflectance)
of the earth amplifying this effect.
Eventually, when we know more about the effects
of the mechanisms involved, fluctuations in cosmic rays could be incorporated in helping model cloud
albedo changes.
The resulting increased / decreased ice is amplified by «various feedbacks, including ice -
albedo, dust, vegetation and,
of course, the carbon cycle which amplify the direct effects
of the orbital
changes.»
From the point
of view
of climate modelling the all - gone moment isn't as important as the magnitude
of the
change in
albedo — particularly in the spring, summer and autumn.
This implies a forcing
of 3 W / m2 for
albedo changes presumably due to additional ice / snow sheets.
The
change in
albedo for such a long period
of time each year is bound to cause all sorts
of weird weather that we have never before experienced.